Annual Variation of Major Ion Constituents in Precipitation Collected
in Yonezawa City

The samples collected in Yonezawa from April 1993 to March 1997 on an event basis were analyzed for pH, electric conductivity (EC) and concentrations of major ions (Na+, K+, NH4+, Ca2+, Mg2+, Cl−, NO3− and SO42−). These data were compared with the interim monitoring reports from Acid Deposition Survey of Japan Environment Agency Phase III. The results of the annual data observed in Yonezawa were as follows: (1) When the annual means of electric conductivity (EC) values were higher, the ones of pH values were lower. (2) Both Na+ and Cl− concentrations in winter were higher about 25 times than the ones in summer, and the EC values were about three times. (3) It was found that the atmosphere in Yonezawa has become worse gradually after 1993, and that the pattern of pAi-pH in Yonezawa was made identification of the one in other areas of Japan.
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